Multiple Antennas

[tesla1886]

In the area I live a directional antenna is better to use then an omni antenna. However like most people, I am sure, I have aerial signals coming from several directions. Although the antenna I have is adjustable with a remote, in today's world of DVRs / PVRs and / or multiple people watching different channels, I do not think it is optimal.

What is the best way to handle this situation? I have read that it is possible to combine the signals from multiple antennas, but I have also read that doing so could be a problem if the combine signals are out of phase. Has any hooked up multiple directional antennas successfully?

If the signals cannot be combined is it possible to install two capture cards into on PVR?

Thank You

[Graham]

If the signals cannot be combined is it possible to install two capture cards into on PVR?

I currently have four devices with a total of eight tuners ... but mine are all connected to the same antenna. There are many folk on here who use an antenna tuner (DVB-T / ATSC) with a satellite tuner. You should be able to get multiple tuners working with each tuner connected to a different antenna.

But ... You will need to do the work to manage the channels in NextPVR. You might receive Channel XYZ from each of two tuners with the signal from one tuner being better than from the other tuner. You might want to delete the weaker version of the channel.

[2leftfeet]

@tesla1886

It is possible to use multiple antennas in your situation.

For example, I currently use five different antennas driving two tuner devices (HDHR Connects). Some of my antennas are combined (phased) to increase gain for certain signals and some are combined, not phased, because I am receiving certain signals from different bands and directions and one of my antennas, a very large, homemade folded dipole-driven yagi, is dedicated to a particular channel (RF channel 2- 57 MHz) which is notoriously hard to receive due to its susceptibility to noise/interference.

This setup works very well for me. Fortunately for me, I am an electrical engineer with a background in RF communications, so its not that hard, except making all this work in the limited space of my house's attic. For others, without knowledge of some of the underlying EM principles, antenna system design can become a rather confusing task.

If you do decide to undertake the task of using muliple antennas, you should be aware of the established rules for combining signals from different directions and from different parts of the RF spectrum. There are also multiple devices that are used to combine signals from the multiple antennas, such as a simple balanced splitter used in reverse, HLSJ's and HVSJ's, filters, attenuators, etc. - each providing certain functions. Also, there is a large selection of antennas in the market, some work better than others, depending on the specific situation.

Everyone's situation is a little different and no one solution to this will fit every need. There are various forums (avsforum.com, rabbitears.info, etc) that offer help to those like you get started. Also, I would advise that you vist http://www.TVFool.com and/or http://www.rabbitears.info and perform a signal analysis for received signal strengths to your location from the various stations in the hood. This signal analysis will provide a clear picture of what exactly you are facing and would allow others to help you in your specific environment.

[mikeh49]

@2leftfeet - great answer. After all that, how's your reception? Picture of your attic or the signal processing center?

[2leftfeet]

Considering that the antenna farm is in the attic, all signals have a 2edge path to station antennas (between 15-25 miles away) and there is a group of trees directly inline between my house the the antenna towers, the reception is quite good. I am getting at least a 28 dB SNR on all desired channels, except channel 2, where the SNR is between 24-25 dB. With the digital cliff sitting at ~15 dB SNR, I have plenty of margin for undisturbed reception even during rain, wind and even snow on the roof.

Pictures would be hilarious - I made the ch2 yagi antenna out of scrap wood, awg14 house wire and an old curtain rod as my reflector, all suspended from rafters. Element spacing is not ideal because of attic space limitations.

[tesla1886]

@tesla1886
Everyone's situation is a little different and no one solution to this will fit every need. There are various forums (avsforum.com, rabbitears.info, etc) that offer help to those like you get started. Also, I would advise that you vist http://www.TVFool.com and/or http://www.rabbitears.info and perform a signal analysis for received signal strengths to your location from the various stations in the hood. This signal analysis will provide a clear picture of what exactly you are facing and would allow others to help you in your specific environment.

Thank you 2leftfeet. I have posted over at avsforum.com

[dgeezer]

My setup is similar to 2leftfeet, but since I am the furthest thing from an electrical engineer it is far simpler. However, it works great.

I have 2 antennas and 2 hdhomerun tuners in my attic connected by cat5e to the server in my basement. One antenna is a store bought yagi pointed at a group of transmitters about 40 miles away. The other antenna is a homemade copper loop mounted on a scrap 2x4. My problem was that one group of transmitters are only about 5 or 6 miles away and I would get multipath interference on one particularly strong station. The tiny folded dipole antenna is weak enough that I get far better reception than with the larger antenna. I was afraid that I would never get combining antennas sorted out.

It's easy enough to restrict each HdHomerun to a particular group of channels. I think that if I do a scan I get about 40 to 50 channels, including subs, on each antenna. Especially now since there aren't any leaves on the trees. I have the lineup restricted to just the strong signals from my local stations.

[p37307]

My favorite channels group went slightly off (but great if it is raining or very cloudy) so I had to make me an antenna just for that transmitter and join it with my main antenna. I had to obstruct part of the homemade one so it wouldn't interfere with channels on the main antenna. It works. Ugly setup but it works.

Don't know the tech speak about it but one set of channels was picking up another set and they were colliding and making the other channels (major networks) lose strength.

Took a lot of playing but got it going.

[UncT]

One thing you should be aware of is that the coax cables going to the separate antennas should be the same length. This prevents standing waves that are interfering. You can use a splitter in reverse but it is best to go on line and find an antenna combiner (outside looks like a splitter but the insides are slightly different). This is my setup for Kentucky and it works really well.

[BrockDorf]

hey...i think you can use an antenna tuner with a satellite tuner. You scan get multiple tuners working with each tuner connected to a different antenna.You might receive Channel XYZ from each of two tuners with the signal from one tuner being better than from the other tuner.

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